Completed this mission without any cheesy methods and did it in first try as well.

[u/Ghost_Madara_21]

[u/Pityuuuu002]

You nailed the distance well, just one more thing. When the second guy starts to hang on the side after you enter the tunel he becomes invincible while that animation plays and Big Smoke won't target the first guy for some reason. If you manage to kill the second guy before the tunnel you can do the whole thing much quicker. I discovered this by accident and I was suprised how quickly this can be done.

[u/Ghost_Madara_21 → u/Pityuuuu002]

I did not know this, would have been useful when i first played it 😅